Research in our laboratory has focused on the composition and metabolism of plasma lipoproteins and apolipoproteins (apo) in normal and dyslipoproteinemic man. Over the past 12 months we have completed analysis of radiolabeled apoA-I and apoA-II studies. These proteins are major constituents of human high density lipoproteins (HDL). A preliminary multicompartmental model for the metabolism of these proteins in man has been developed. Research on the interaction of radiolabeled apoA-I and apoA-II with native apolipoproteins and HDL has been completed. Radiolabeled apoC-II and apoC-III2 studies have been completed in normal subjects. The metabolism of apoE, isolated from normal and dyslipoproteinemic patients (type III and type V hyperlipoproteinemia) has been studied in normal and type III patients. ApoC-II, apoC-III2 and apoE are protein constituents of very low density lipoproteins (VLDL) and HDL. Analysis of human thoracic duct lymph lipoprotein and apolipoprotein 24 output data has been completed, as have incubation studies with lymph chylomicrons and lipoprotein lipase. In addition the effects of high cholesterol and high fat diets on plasma lipoproteins in normal subjects has been studied.